1. Field of the Invention
The invention generally relates to a signal generating apparatus, in particular, to a power on reset signal generating apparatus.
2. Description of Related Art
A power on reset signal generating apparatus is widely used in nowadays integrated circuits. The power on reset signal generating apparatus is built-in a system, and generates a power on reset signal after a supply voltage provided to the system rising stable. The power on reset signal is used to reset the digital circuits in the system to prevent the digital circuits to enter an unknown state.
In the prior art, the power on reset signal generating apparatus always need a large size capacitor for generating the power on reset signal with an effective width. That is, the circuit area of the power on reset signal generating apparatus is large, and the cost of the system is increased.